Question

There are many things that differentiate the structure and function of prokaryotes compared to eukaryotes. Summarize the process of eukaryotic gene regulation and explain why this process if different from the operon model of gene regulation in prokaryotes.

Answer 1

The expression of eukaryotic genes is controlled primarily at the level of initiation of transcription, although in some cases transcription may be attenuated and regulated at subsequent steps. As in bacteria, transcription in eukaryotic cells is controlled by proteins that bind to specific regulatory sequences and modulate the activity of RNA polymerase. The intricate task of regulating gene expression in the many differentiated cell types of multicellular organisms is accomplished primarily by the combined actions of multiple different transcriptional regulatory proteins. In addition, the packaging of DNA into chromatin and its modification by methylation impart further levels of complexity to the control of eukaryotic gene expression.

Prokaryotic transcription and translation occur simultaneously in the cytoplasm, and regulation occurs at the transcriptional level. Eukaryotic gene expression is regulated during transcription and RNA processing, which take place in the nucleus, and during protein translation, which takes place in the cytoplasm.It turns out that the regulation of such genes differs between prokaryotes and eukaryotes. For prokaryotes, most regulatory proteins are negative and therefore turn genes off. For instance, some repressors bind near the start of mRNA production for an entire operon, or cluster of coregulated genes.